This invention relates to computed tomographic (CT) imaging, and more particularly to methods and apparatus for the detection and diagnosis of lung abnormalities.
In spite of recent advancements in computed tomography (CT) technology, such as faster scanning speeds, larger coverage with multiple detector rows, and thinner slices, energy resolution is still a missing piece. Namely, wide x-ray photon energy spectrum from the x-ray source and the lack of energy resolution from CT detection systems preclude energy discrimination CT.
X-ray attenuation through a given object is not a constant. Rather, the X-ray attenuation is strongly dependent on the x-ray photon energy. This physical phenomenon manifests itself in the image as beam-hardening artifacts, such as, nonuniformity, shading, and streaks. Some beam-hardening artifacts can be easily corrected, but other beam-hardening artifacts may be more difficult to correct. In general, known methods to correct beam hardening artifacts include water calibration, which includes calibrating each CT machine to remove beam hardening from materials similar to water, and iterative bone correction, wherein bones are separated in the first-pass image then correcting for beam hardening from the bones in the second-pass. However, beam hardening from materials other than water and bone, such as metals and contrast agents, may be difficult to correct. In addition, even with the above described correction methods, conventional CT does not provide quantitative image values. Rather, the same material at different locations often shows different CT numbers.
Another drawback of conventional CT is a lack of material characterization. For example, a highly attenuating material with a low density can result in the same CT number in the image as a less attenuating material with a high density. Thus, there is little or no information about the material composition of a scanned object is based solely on the CT number. At least some state-of-the-art CT scanners currently available are limited to providing anatomical information. For lung scans, images produced by such scanners exhibit a significant level of image artifacts and CT number inaccuracy. These limitations prevent the utilization of the CT device for advanced diagnosis. Accordingly, the methods and apparatus described herein address the detection and diagnosis of lung abnormalities.
In one aspect, a method for obtaining data is provided. The method includes scanning a lung of a patient with a Multi-Energy Computed Tomography (MECT) system to acquire data regarding a plurality of contrast agents
In another aspect, a Multi-Energy Computed Tomography (MECT) System is provided. The MECT includes a radiation source, a radiation detector, and a computer operationally coupled to the radiation source and the radiation detector. The computer is configured to receive data regarding a first energy spectrum of a scan of a lung of a patient, receive data regarding a second energy spectrum of the scan of the lung, generating a first functional image using data regarding a first contrast agent, and generating a second functional image using data regarding a second contrast agent.
In yet another aspect, a Multi-Energy Computed Tomography (MECT) System is provided. The MECT includes a radiation source, a radiation detector, and a computer operationally coupled to the radiation source and the radiation detector. The computer is configured to receive data regarding a first energy spectrum of a scan of a lung of a patient, receive data regarding a second energy spectrum of the scan, and decompose the received data to generate data regarding a plurality of contrast agents.
In still another aspect, a computer readable medium is encoded with a program. The program is configured to instruct a computer to receive data regarding a first energy spectrum of a scan of a lung of a patient, receive data regarding a second energy spectrum of the scan, and decompose the received data to generate data regarding a plurality of contrast agents.
In yet still another aspect, a computer readable medium is encoded with a program. The program is configured to instruct a computer to scan a lung of a patient with a Multi-Energy Computed Tomography (MECT) system to acquire data regarding a first contrast agent in a gaseous medium and a second contrast agent in a liquid medium, generate a first functional image using data regarding the first contrast agent, and generate a second functional image using data regarding the second contrast agent.
In another aspect a method for obtaining data is provided. The method includes administering a gaseous contrast agent to a patient, administering a liquid contrast agent to the patient, and imaging the patient to obtain data regarding the gaseous contrast agent and the liquid contrast agent.